This disclosure relates generally to image or video processing and more specifically relates to processing pixels and associated sub-blocks within a macroblock of an image or video frame. Video processing systems are employed in various demanding applications, including high-definition television, missile guidance systems, and Internet video streaming. Such applications often demand compact cost-effective systems for encoding, transmitting, and decoding high quality compressed video relatively accurately, quickly, and efficiently.
Standards such as H.264 define specific ways of doing video encoding and decoding. H.264 is a digital video codec standard written by the Joint Video Team (JVT) comprising the International Telecommunication Union (ITU)—Telecommunication Standardization Sector (T) and the International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC) Moving Picture Experts Group (MPEG). The H.264 standard is also called, the ISO/IEC MPEG-4 Part 10 standard or the ITU-T H.264 standard.
In an example H.264 system, pixels of a video image are logically grouped into 16×16 blocks of pixels called macroblocks. Each macroblock is grouped into sixteen 4×4 blocks of pixels, called sub-blocks. The image is partitioned into groups of contiguous macroblocks in coding order, called slices, each containing several macroblocks. When this example H.264 system processes a slice, information from one or more previously processed macroblocks is typically required before a subsequent macroblock is processed. Similarly, when processing sub-blocks within a macroblock, information from one or more previously processed sub-blocks is typically required before a subsequent sub-block is processed. Improvements in the speed and efficiency of implementing H.264 functions such as processing macroblocks, sub-blocks, or other data can lead to a better performing, lower cost, or otherwise more desirable system or product.